Valve for rock drills



June 7, 1932. F. M. SLATER VALVE FOR ROCK DRILLS Filed Dec. 5-, 1931 w azyev w y IN VEN TOR.

fILS ATTORNEY.

I FRED M. SLATER, OF EASTON,

Patented June 7, 1932 UNITED STATES PANY, F JERSEY CITY,

PATENT OFFICE VALVE non nocx DRILLS Application filed December 5, 1931. Serial No. 579,193.

This invention relates to rock drills, but more particularly to a distributing valve for rock drills of the fluid actuated type.

One object of the invention is to assure a rapid action of the distributing valve and, in consequence, a rapid reciprocatory move ment of the piston which the valve controls.

Other objects will be in part obvious and in part pointed out hereinafter.

In the accompanying drawing and in which similar reference characters refer to similar parts,

Figure 1 is a sectional elevation of a rock 7 drill equipped with a valve constructed in accordance with the practice of the invention and showing the valve in position for admitting pressure fluid into the piston chamher to actuate the piston on its working stroke, and

Figure 2 is a similar view showing the valve in position to admit pressure fluid into the front end of the piston chamber for actuating the piston rearwardly.

Referring more particularly to the drawing, A designates, in general, a rock. drill comprisin a cylinder B having a piston chamber to accommodate a reciprocatory hammer piston D. The piston chamber C is 7 provided with a free exhaust port E which is controlled by the piston D.

At the front end of the cylinder B is a front head F having a chuck H arranged therein to accommodate the shank of a working implement, such as a drill steel J, to

which the blows of the hammer piston D are transmitted by an anvil block K. ;The anvil block is guided by a front cylinder washer L interposed between the cylinder B and the front head F.

S of the valve chamber by a boss V carried by a back head WV which is seated on the rear end of the valve chest The admission of pressure fluid to the valve chamber Q is controlled by a throttle valve X in the back head W and such pressure fluid is conveyed into the valve chamber by a'supply passage Y leading from the throttle valve X through the back head W and the valve chest P and opening into the front end of the enlarged portion S of the valve chamber.

The pressure fluid utilized for actuatin the piston D forwardly on its working stroke is conveyed into the rear end of the piston chamber C by a rear inlet passage Z in the Valve chest P and which opens into the re duced portion R of the valve chamber at a point preferably near the rear end of the said reduced portion. The pressure fluid utilizedfor actuating the hammer piston D rearwardly is conveyed to the front end of the piston chamber C by a front inlet passage which opens with its rear end into the enlarged portion S of the valve chamber at a point intermediate the ends of said enlarged portion S.

In the periphery of the reduced portion U of the valve T and at the rear end of said reduced portion is an annular groove 0 which, as the valve T reciprocates inthe valve chamber Q, establishes communication between the supply passage Y and the inlet passages Z and b. At the forward end of the enlarged portion or head d of the valve T'is an actuating surface 0 which is constantly exposed to pressure fluid and across which pressure fluid flows to the inlet passages Z and b. 1

In the rear end of the head d of the valve is a pressure chamber into which extends an'extension g of the back head WV to form a closure for said pressure chamber f, and in the valve T are a pair of crosspassages h which communicate at their outer ends with the annular groove 0. p p Y Communicating with'the cross passages h is a passage j which extends longitudinally of the valve T. The rear end of the passage j opens into the pressure chamber f while the front end of the passage opens into the reduced portion R of the valve chamber.

The front end of the valve constitutes a pressure surface which is constantly exposed to pressure fluid flowing through the passage j. Similarly, the bottom of the recess or pressure chamber 7 constitutes a pressure surface 0 which is constantly subjected to pressure fluid supplied thereto through the passage Leading from the front end of the reduced portion R of the valve chamber is a trip passage 0 which communicates with the piston chamber C at a point immediately forwardly of the main exhaust port E, and a trip passage 9 leads from the pressure chamber 7' to the piston chamber C wherewith it communicates at a point immediately rearwardly of the exhaust port E.

On the rear end of the head (Z of the valve is an actuating surface 1* which lies within an annular pressure chamber 8 defined by the wall of the enlarged portion S of the valve chamber Q and the extension 9. The admission of pressure fluid to the pressure chamber 8 is effected by a passage 23 which leads from said pressure chamber and, in the present instance, communicates at its opposite end with the inlet passage Z.

In order tov provide anescape for compression from the rear end of the piston chamber C the reduced portion U of the valve is provided with an annular groove to in its periphery to establish communication between the rear inlet passage Z and an atmospheric vent 0 extending through the valve chest P and the cylinder B. Similarly, in the periphery of the head cl of the valve is an annular groove w to establish communication between-the front inlet passage 6 and a vent 02 leading from the enlarged portion S of the valve chamber to the atmosphere.

The operation of the device is as follows:

; IVith the valve T in its foremost limiting position in the valve chamber Q and the piston in the rearmost limiting position in the piston chamber C pressure fluid may flow from the supply passage Y through the annular groove 0 and the rear inlet passage Z into the rear end of the piston chamber to drive the piston D forwardly against the anvil block K.

During the admission of pressure fluid into the rear end of the piston chamber pressure fluid will flow from the annular groove ethrough the passages h and j into the pressure chamber f and into the front end of'the valve chamber. At the same time, however, pressure fluid will flow from the inlet passage Z to the passaget into the pressure chamber .9 and act against the actuating surface 0" so that a preponderat-ing area is exposed to pressure fluid tending to hold the valve in its foremost position.

continue to flow through these channels until the piston D moves forwardly to cover the trip passage 9. Thereafter pressure fluid will accumulate within the front endof' the valve chamber Q until-it reaches full line pressure. Such pressure, however, will be ineffective to disturb the position of the valve until the piston D. communicates the rear end of the piston chamber C with the atmosphere. The pressure fluid will then be exhausted from the pressure chambers s and f together with that employed for actuating the piston D forwardly. The pressure fluid entrapped in the front end of the valve chamber Q and that flowing across the actuating surface 0 will then move the valve rearwardly to the position illustrated in Figure2 and will hold the valve immovable in that position.

In the new position :ofthe valve the :annular groove 0 communicates with the front inlet passage 1) so that pressure fluid will flow into the front endof-thepiston chamber C and drive-the piston D rearwardly. Afterthe piston Dihas opened. the front end of the piston chamber to; the atmosphere thepress sure fluid is exhausted from the frontend of the piston chamber together with that in the front end of the valve chamber Q. The valve T will then again be reversed in the manner previously described. I

As will be observed, when the valve occupies its foremost limiting position toadmit pressure'fluid into the piston chamber for driving the piston forwardly, the annular groove w will register with the front inlet passage?) and the vent w. The air existing in thefront end ofthe piston chamber C may then be expelled through these passages to the atmosphere instead of being: compressed. In like manner, when the piston D is being actuated rearwardly the air may be'expel led from the rear end of the piston chamber through the rear inlet passage Z, the annular groove 1:. and the vent o to the atmosphere. 3

1. In a fluid actuated rock drill, the combination of a cylinder having a piston chamber and a piston in the piston chamber, a valve chest having a valve chamber, a valve in the valve chamber to distribute pressure fluid to the piston chamber, a pair of opposed pressure surfaces constantly exposed to pressure fluid for throwingflthe valve, passages controlled by thepistonfor intermittently relieving the pressure fluid acting, against the pressure surfaces, an actuating surface constantly exposed to pressure fluid to assist in throwing the valve in one direction, and

an opposed actuating surface on the valve intermittently exposed to pressure fluid to assist in throwing the valve in the opposite direction.

2. In a fluid actuated rock drill, the combination of a cylinder having a piston chamber and a piston in the piston chamber, a valve chest having a valve chamber, a valve in the valve chamber to distribute pressure fluid to the piston chamber, a pair of opposed pressure surfaces constantly exposed to pressure fluid for throwing the valve, passages controlled by the piston for intermittently relieving the pressure fluid acting against the pressure surfaces, an actuating surface constantly exposed to pressure fluid to assist in throwing the valve in one direction, and an opposed actuating surface on the valve intermittently exposed to pressure fluid flowing from the valve chamber to an end of the piston chamber to assist in throwing the valve in the opposite direction.

3. In a fluid actuated rock drill, the combination of a cylinder having a piston chamber and a piston in the piston chamber, a valve chest having a valve chamber, a valve in the valve chamber to distribute pressure fluid to the piston chamber, a pair of opposed pressure surfaces constantly exposed to pressure fluid for throwing the valve, trip pas sages leading from the pressure surfaces to the piston chamber and being controlled by the piston for intermittently relieving the pressure fluid acting against the pressure surfaces, an actuating surface over which pressure fluid flows to both ends of the piston chamber and being constantly exposed to pressure fluid to assist in throwing the valve in one direction, and an opposed actuating surface on the valve intermittently exposed to pressure fluid during the admission of pressure fluid to one end of the piston chamber to assist in throwing the valve in the opposite direction.

In testimony whereof I have signed this specification.

FRED M. SLATER. 

